In the practice of root canal therapy, sometimes referred to as endodontia, it becomes necessary to scrape or abrade the wall of the canal prior to filling the same. Such removal is accomplished by using what are termed "files" or "reamers" which are reciprocated manually within the canal to prepare the same for the filling step by cleaning and shaping. Since the implements employed, whether files or reamers, function in essentially the same way, it will be convenient, for conciseness in the instant disclosure, to refer to the same broadly as "files". The implement is provided with a handle to improve the grip. Although, a mechanical apparatus to perform this digital function is known, it has not met with acceptance, no doubt for the reason that optimum control of the tool is a matter of feel through the fingertips. The importance of reliable grip and feel becomes even more evident when it is remembered that a typical file is approximately 25 mm. in length measured outwardly from the handle and that a typical handle is about 3 to 4 mm. in diameter and 8 to 9 mm. in length. Although operators use a rubber dam to preclude swallowing by the patient of a dropped file, there is nevertheless an everpresent hazard which it is necessary to anticipate and avoid by assuring a firm but sensitive grip.
Present forms of handle are cylindrical and, therefore, are not conducive to reliable gripping.